U.S. Pat. No. 4,057,204 issued Nov. 8, 1977 in the name of R. E. Zajac to Windings, Inc. ("Zajac") discloses a payout tube of the above described sort in which an annular flange encircles the tube near its exit end to provide a planar stop surface extending continuously around the tube and the tube has at such end, axially outward of the flange, on diametrically opposite sides of the tube, a pair of projections which extend radially out from the tube to lie over the flange and which are shown as being of triangular cross section in planes normal to the radial center lines of the projections. The walls of such projections towards that flange are planar and slope in opposite directions as seen in a direction along the tube diameter between those center-lines.
The Zajac tube is secured in position within the container by (a) providing in a wall of the container a circular hole of the tube's diameter and having equangularly spaced around it a pair of notches formed in the hole's circumference for receiving the tube projections, (b) positioning the tube inside the container to pass a stub portion of such tube through such hole and such projections from inside to outside through such notches until the tube flange bears against the inside of such wall around the circumferential margin of the hole, and (c) then turning the tube 90.degree. to cause portions of the wall around the tube to be interposed between such flange and the tube projections to thereby secure the tube to the wall. According to the Zajac patent as it is understood, what happens in the course of such turning is that, because the space between the flange and the axially inner edges of the sloping projection walls towards the flange is a space less then the wall thickness of the container, the turning of the tube causes the inclined lower surfaces of the projections to ride up on the box material and grip into it to prevent accidental turning of the tube to an improper position. The Zajac patent also indicates in its abstract that improper turning of the tube is avoided because the effect of the tube projections on the box material is that the projections "dig into it".
The Zajac tube has the disadvantage that, because the space between the flange and the axially inner edges of the sloping projection is less than the thickness of the wall of the container, it is relatively difficult to initially insert portions of that wall between such flange and those inner edges. Moreover, it is thereafter very difficult (because of high friction between the wall and the tube) to relatively turn the tube and container about by 90.degree. as taught by Zajac. Another disadvantage of the Zajac tube is that any such tube with a particular spacing between its flange and the inner edges of its projections is limited to a relatively restricted range of the thickness of container wall with which the tube can, as a practical matter, be used.